Gas cushion vehicles

ABSTRACT

A gas cushion vehicle provided with one or more lift fan duct sealing valves for maintaining gas cushion pressure in the event of lift fan stoppage wherein a sealing valve comprises a flexible valve membrane arranged across the cushion end of the or each gas duct leading from the or each lift fan to the cushion, the membrane being flexibly movable into an open position clear of the end of the duct when the lift fan is operating and movable into a closed position so as to close the end of the or each duct when the or each lift fan associated with the or each duct is not operating and the gas pressure acting within the cushion is higher than the gas pressure acting within the or each duct.

United States Patent 1191 Dy 1451 Nov. 11, 1975 1 GAS CUSHION VEHICLES['75] Inventor: Raymond William Dyke,

Southampton, England [73] Assignee: Vosper Thornycroft Limited,

- Porstmouth, England 1 Filed: Dec. 26, 1973 211 Appl. 1516.; 427,537

[30] Foreign Application Priority Data May 7, 1973 United Kingdom21642/73 [52] US. Cl. 180/117; 180/128 [51] Int. Cl. B60V 1/16 [58]Field of Search 180/116, 117, 118,119, 180/120, 121,126,127,128;137/493, 525, 525.3

[56] References Cited UNITED STATES PATENTS 1,051,738 1/1913 Kavanagh137/5253 X 3,099,288 7/1963 Weis 137/5253 3,425,505 2/1969 Jones 180/1183,481,423 12/1969 \Vinter... 180/127 X 3,552,519 1/1971 Wren 180/1243,601,214 8/1971 Bertin 180/118 3,618,695 11/1971 Wheeler 180/1283,643,758 2/1972 Winter", 180/128 FOREIGN PATENTS OR APPLICATIONS1,300,751 12/1972 United Kingdom 180/116 Primary Examiner-Kenneth 1-1.Betts Attorney, Agent, or F irmNorris '& Bateman 57 ABSTRACT A gascushion vehicle provided with one or more lift fan duct sealing valvesfor maintaining gas cushion pressure in the event of lift fan stoppagewherein a sealing valve comprises a flexible valve membrane arrangedacross the cushion end of the or each gas duct leading from the or eachlift fan to the cushion, the

membrane being flexibly movable into an open position clear of the endof the duct when the lift fan is operating and movable into a closedposition so as to close the end of the or each duct when the or eachlift fan associated with the or each duct is not operating and the gaspressure acting within the cushion is higher than the gas pressureacting within the or each duct.

4 Claims, 1 Drawing Figure US. Patent --Nov. 11, 1975 1 GAS CUSHIONVEHICLES The present invention relates to a gas cushion vehicle and moreparticularly to a non-return valve in a gas cushion vehicle arranged soas to prevent gas contained within the cushion from escaping by reverseflow through the lift fans in the event of a lift fan stoppage.

In U.S. Pat. No. 3,425,505 (equivalent to UK. application No. 18,564/65)there is described a gas cushion vehicle provided with flaps movable toclose off the ducts between the lift fans and the gas cushion so as toprevent gas reversing up the ducts in the event of lift fan failure.Such flaps were controlled by a complicated mechanical and hydraulicarrangement which was expensive to provide and being complicatedrequired careful maintenance.

It is usual for the gas to be pressurised by one or more lift fans andsupplied through a duct or ducts to the or each cushion. If the lift fanor one of the lift fans fails it is desirable to prevent the loss of gasfrom said cushion or cushions by reverse flow through the inoperativelift fan.

In an attempt to simplify the arrangement for closing off the ductsthere was designed and installed in one of our vehicles a valvecomprising one or more invertible segments of flexible material. Thisarrangement is described in my U.K. Pat. No. 1,300,751 (equivalent toUS. application No. 228,774, filed Feb. 23, 1972, now US. Pat. No.3,841,433). When the segment inverted there was a tendency for thepoints of attachment of the segment to the valve frame to wear. Also thevalve itself was large and the valve casing cumbersome resulting in someloss of efficiency in the lift system.

An object of the present invention is therefore to attempt to overcomethese disadvantages.

The present invention consists of a gas cushion vehicle having a hullprovided with one or more lift fans and a duct from the or each fan tothe gas cushion, a noninvertible flexible valve membrane arranged acrossthe cushion end of the or each duct, the membrane being flexibly movableinto an open position clear of the end of the duct when the lift fan isoperating and movable into a closed position so as to close the end ofthe or each duct when the or each lift fan associated with the or eachduct is not operating and the gas pressure acting within the cushion ishigher than the gas pressure acting within the or each duct, whereby onlift fan stoppage the duct is sealed.

The arrangement is such that only one flexible membrane need be providedfor each duct or group of ducts; the membrane being non-invertible thereis less wear; and because the space required for the membrane to operateis minimal, the membrane also can be fitted in a vehicle having aflexible skirt within the existing space between the end of the duct andthe skirt and within the upper part of the flexible skirt. Because themembrane is clear of the end of the duct the flow in the duct isuninterrupted, and the duct resistance kept minimal.

The invention will now be described with reference to a drawing, whichshows one embodiment of the invention by way of example, in whichdrawing the FIG- URE shows a diagrammatic cross-section of a cushionsupply duct and flexible skirt with valve membrane in a gas cushioncraft according to the invention.

In the drawing can be seen part of the hull l of a gas cushion vehiclehaving a flexible skirt 2. The skirt 2 has an upper part 3 formed of anouter loop 4 and inner loop 5. The skirt 2 has a lower part 6 formedfrom a main segment 7 and inner segment 8. Within the hull 1 of thevehicle is a lift fan duct 9 having an end 10 which opens into alongitudinal space 11 formed within the upper part 3 of the skirt.Across the duct end 10 is a flexible membrane 12 attached to the outerloop 4 at 13 and to the hull at 14.

When the lift fan (not shown) is operating air is blown down the duct 9into space 11 forcing the membrane 12 into the position shown by theunbroken line in the drawing. Air is then deflected longitudinally alongthe space 11 by the membrane and flows down into the main and innersegments 7 and 8 into the gas cushion.

When a lift fan stops, there is a reversal of air flow in theinoperative fan duct, due either to air supply from other fans or tocushion pressure leaking to atmosphere. This flow blows the membrane 12into the position 15 shown by the broken line, so as to block the fanduct end 10 and seal the duct 9.

I claim:

1. A gas cushion vehicle having a hull provided with lift fan means,duct means leading from the fan means to the gas cushion and having anoutlet, a flexible valve membrane having a pair of substantiallyparallel edges which are attached to the hull on opposite sides of saidoutlet so that the membrane extends across said outlet, whereby themembrane is flexibly movable into an open position clear of said outletwhen the lift fan means is operating and is movable into a closedposition so as to close said outlet when the lift fan means is notoperating and the gas pressure acting within the cushion is higher thanthe gas pressure acting within the duct means, and a flexible skirtattached to said hull, with one of said edges of the valve membraneattached to said flexible skirt.

2. A gas cushion vehicle as claimed in claim 1, wherein the other ofsaid edges of the valve membrane is attached directly to the hull of thevehicle.

3. A gas cushion vehicle as claimed in claim 1, wherein said flexibleskirt comprises an outer loop and an inner loop, said one of said valvemembrane edges being attached to said outer loop of the flexible skirt.

4. A gas cushion vehicle having a hull provided with lift fan means,duct means leading from the fan means to the gas cushion and having anoutlet, and a flexible valve membrane having a pair of substantiallyparallel edges which are attached to the hull on opposite sides of saidoutlet so that the membrane extends across said outlet, whereby themembrane is flexibly movable into an open position clear of said outletwhen the lift fan means is operating and is movable into a closedposition so as to close said outlet when the lift fan means is notoperating and the gas pressure acting within the cushion is higher thanthe gas pressure acting within the duct means, one of the edges of saidvalve membrane being attached directly to said hull.

1. A gas cushion vehicle having a hull provided with lift fan means, duct means leading from the fan means to the gas cushion and having an outlet, a flexible valve membrane having a pair of substantially parallel edges which are attached to the hull on opposite sides of said outlet so that the membrane extends across said outlet, whereby the membrane is flexibly movable into an open position clear of said outlet when the lift fan means is operating and is movable into a closed position so as to close said outlet when the lift fan means is not operating and the gas pressure acting within the cushion is higher than the gas pressure acting within the duct means, and a flexible skirt attached to said hull, with one of said edges of the valve membrane attached to said flexible skirt.
 2. A gas cushion vehicle as claimed in claim 1, wherein the other of said edges of the valve membrane is attached directly to the hull of the vehicle.
 3. A gas cushion vehicle as claimed in claim 1, wherein said flexible skirt comprises an outer loop and an inner loop, said one of said valve membrane edges being attached to said outer loop of the flexible skirt.
 4. A gas cushion vehicle having a hull provided with lift fan means, duct means leading from the fan means to the gas cushion and having an outlet, and a flexible valve membrane having a pair of substantially parallel edges which are attached to the hull on opposite sides of said outlet so that the membrane extends across said outlet, whereby the membrane is flexibly movable into an open position clear of said outlet when the lift fan means is operating and is movable into a closed position so as to close said outlet when the lift fan means is not operating and the gas pressure acting within the cushion is higher than the gas pressure acting within the duct means, one of the edges of said valve membrane being attached directly to said hull. 